Unit 2 Mechanical Modification
- 1. UNIT - II Mechanical Modification – Principles of soil densification – Properties of Compacted soil,Compaction control tests, Specification of compaction requirements, BlastingVibrocompaction, Dynamic Tamping and Compaction piles. By Mamidala Prudhvi Assistant Professor
- 2. What is densification of soil In geotechnical engineering, soil compaction is the process in which stress is applied to a soil causes densification as air is displaced from the pores between the soil grains. ... Affected soils become less able to absorb rainfall, thus increasing runoff and erosion
- 3. INTRODUCTION TO THE COMPACTION OF SOILS
- 4. INTRODUCTION Soil is used as a construction material for constructing embankments and subgrades. Embankments are constructed to raise the ground level above the existing level up to the formation level to support buildings, roads, or railways or other structures and also to retain water as in the case of earth dams or canal banks
- 5. The stability and durability of the embankments and subgrades depends on the improvement of shear strength of the soil as well as the restriction of settlements or deformation within permissible limits. The strength and deformation characteristics of embankments and subgrades depend directly on the density of the soil
- 6. Definition of Compaction Compaction is the artificial and mechanical process of decreasing the volume of the soil rapidly by the expulsion of air voids in the soil resulting in the increase in density. Densification of soil also occurs naturally due to consolidation of foundation soils by expulsion of pore water due to loads from the structure. This is a rather long-term process compared to compaction
- 7. Principle of Compaction . • The principle of compaction was developed by R. R. Proctor in 1933 during construction of earth dams in California • The objective of compaction is to achieve maximum possible dry density of the compacted soil. . • The water content used for compaction controls the dry density achieved
- 8. shows the variation of the dry density with water content
- 9. The following are some of the objectives of compaction: Increase the shear strength of soil. Decrease the undesirable settlement of structures. Control undesirable volume change. Decrease permeability of soil. Increase the bearing capacity of foundations. Increase the stability of slopes
- 11. COMPACTION CONTROL TESTS Compaction control tests are essential to check whether the objectives of compaction are achieved. It is difficult to check the objectives directly and properties strength and compressibility are assessed indirectly. Control tests in terms of water content, density, penetration resistance are conducted.
- 12. Compaction Control Procedures These specifications are expected to ensure an expected level of performance (in terms of shear strength, compressibility, permeability which are related to bearing capacity, settlements and drainage and seepage etc) Field compaction control tests are specified, and the results of these become the standard for controlling the project. After the earth structure is designed, the compaction specifications written. Laboratory tests are conducted on samples of the proposed borrow materials to define the properties required for design.
- 20. DYNAMIC TAMPING